The present invention relates to the field of roofing, and more particularly, non-metallic roofing such as asphalt composition.
2. Prior Art
Asphalt composition roofing materials are very well known in the prior art. These materials are relatively inexpensive and of light weight, thereby finding wide usage. Asphalt composition materials have been folded for various purposes, such as providing improved sealing characteristics and providing areas of increased thickness which create a three-dimensional appearance. Such folding is limited, with the resulting roof again having a highly repetitive design, lacking depth and texture as is generally characteristic of asphalt composition roofs. Examples of such folding may be found in U.S. Pat. Nos. 1,410,299; 1,435,623; 1,596,272; 1,848,965; 1,975,986; 2,253,753; and 3,913,294. In recent years, to enhance the appearance of asphalt composition roofs, various techniques have been used, including varying the thicknesses of the asphalt layer on the base material to provide texture, and use of different color granules on the lower portion of the shingle to provide a shading effect to create an illusion of a deeper three-dimensional roof. In general, the folding of the asphalt composition was difficult and cumbersome and often caused cracking about the folding line.